The most common and widely used mechanism for converting linear motion to rotational motion, includes a piston moving in a cylinder and rotating the crank shaft by means of a connecting rod. This mechanism has a drawback: through all of its movement the piston is subject to a lateral force pressing it against the cylinder's wall. This increases frictional resistance to the active force.
Another type of mechanism is used in the “Dwelling Scotch Yoke Engine”, U.S. Pat. No. 5,331,926, Jul. 26, 1994. This engine uses a mechanism for converting linear motion of the piston in to rotational motion of the flywheel using the piston and rod with scotch yoke as one solid part. This changes the kinematics and action of the forces but still creates the force, which acts off of the piston axis. The bushing in the cylinder block is used to guide the rod and prevents the piston from experiencing of this force.